The present invention relates generally to lifts and, more particularly, to an improved latching mechanism for the retention ramp of the load platform of a liftgate or other load elevator.
A truck liftgate comprises a load platform mounted at the rear end or tailgate of the body of the truck in a manner to be movable between transit and load bearing positions. In many types of liftgates, where the rear edge of the platform is not made with an integral ramp to define the transition surface between ground level and the load bearing upper surface of the load platform, the relatively blunt rear end of the platform is fitted with a pivotally mounted plate that can be swung between a ramping position as an extension of the platform wherein its rear edge or lip engages the ground and a stowed position overlying the upper surface of the load platform. This plate is sometimes fitted with a mechanism whereby the plate can be held in an erect or upstanding position relative to the horizontally extended load platform and so provide a barrier to keep wheeled carts or other freight from displacement beyond its rear edge. Hence, the plate is commonly called a retention ramp, reflecting its dual function.
In the prior art, the set of hardware to hold the plate in the erect retention position typically comprises a pair of short lengths of chain, sometimes axially spring-loaded, mounted on the surface of the opposite sides of the load platform and a pair of brackets welded to opposite sides of the ramp in alignment with the chain positions. When certain links of the pair of chains, e.g., the second link from the free end, are fitted into slots of the pair of brackets, the retention ramp is then held in the desired position. Another set of hardware is used to hold the retention ramp in a folded position overlying the upper surface of the load platform. Thus, one side of the retention ramp may have a spring-loaded bayonet latch, whose point is engageable with an aperture in a bracket carried on the surface of the load platform. The bayonet latch has a handle closely overlying the platform surface when the retention ramp is in the stowed position thus affording only a slight clearance for the hand or knuckles of the driver in pulling the bayonet latch out of locked position against the force of the spring.
As all of these components of the two hardware sets are surface mounted on the retention ramp and platform they present obstacles to the loading and unloading of freight as well as presenting a danger of tripping for an unwary driver. The devices are also cumbersome in use as they require the driver to ensure that the proper links of the chain lengths be securely anchored in the corresponding bracket slots and that the bayonet latches be properly manipulated to successfully lock the retention ramp in the stowed position to avoid an unlocked retention ramp that will bang against the platform when the truck is in transit from place to place. These devices involve an undue multiplicity of separately attached sets of hardware which is therefore relatively expensive and, as the hardware sets are carried in exposed positions prone to being damaged, they entail excessive maintenance expense.
The present invention obviates the foregoing and other disadvantages of prior art mechanisms.